Manufacture of cold-drawn seamless tubes.



H. VON FORMER.'

MANUFACTURE OF COLD DRAWN SEAMLESS TUBES.

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H. VONFORSTER. MANUFA'CTURE 0F com DRAwN SEAMLESS TUBES.

` APPLICATION F|LED JULY 5, 914.4 Y 1,205,292. l Patented Nov. 21, 1916.

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MANUFACTURE (1E-now nRAwN SEAMLESS TUBES.

-APPLICATION FLED JULY 16| 19ML T l l Patented INGV. 21, 1916.

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l3, wherein t represents t rapidly approaches the ultimate breaking strength and renders the further operation diicult. This will be a parent fro Fig.

l lie tensile .f the ultimate ductile stren h, and f the u til; mate breaking strength. n the new process', on the contrary, hardnessl occurs more '3u the surface Whereas the interior retains its ductility for a considerably lo er pet'iod of time as will be apparent rom Fig. 4.

Whereas it was found uneconomicah in the medi'ately succeed the foregoing pass1 In this'case theheat generated by the change in form is not lost as in the old nocees where the work takes place periodically but is utilized and increased by the immediate succeion of the passes. This heat serves in the first place to ,reduce the hardness and brittleness naturally occurring on the sur face and also to reduce the increase of the ultimate state of fluidity toward the ultimate breaking strength. The manufacture is also considerably simplified by the present invention for whereas the tubes were manufactured hitherto in stages, each stage bei interrupted b the annealing process whikdli occupied suchr a considerable length of time, the' tube can now be manufactured in one stage without being transported. This of course considerably reduces the cost and time as -Well as the works fittings and enables the tubes to be turned out with great rn idity.

eferring now to Figs. 5 and 6 of the' drawings, a' designates the legs o: the drawbench, and I) the blank which is fitted upon a. mandrel c reduced in thickness at the right hand end so as to receive the smallest die. The blank is fitted over the thicker part of the mandrel up to the shoulder thereon at the junction therewith of the reduced part, Mounted on the bed c of the draw bench is a plurality of die holders g in which the dies f nre mounted. the *die holders g being slidable over the reduced part of the mandrel c. The die holders g are adapted to be moved in turn up to the shoulder on the mandrel c. One of the die holders f," is shown in this position ready for the drawing operation.

LLounted'on the power shaft'z is n crank k whlch'trnnsmits motion to :i forked or paralle l level' m through the connecting rod Beneath the bed of the machine is a runway n which may be dovetailed to receive a slide o which carries two projecting pins p and qat each aide. The pin en ages a slot m1 in the lever m so that t e side o is reciprocated in the runway n by the lever m.

Pivoted on the pins genre fingers r under the action of springs t tween the lin ers r and a projection a on the slide o. In t e o sition shown the fin ers r more the first ieholder y over-the Iank b and as soon as the crank k has reached its'other dead position the lever m and slide o return, the fin rs r leaving the die-holder g at the rear engeof the machine. In the meantime the next die-holder g has been moved up to the shoulder on the mandrel c so that the fin ers r pass beneath the pins It of this dieho der `and engage 4 behind the same under the action of the springs t so that the parts are then in position for the next drawin his process is repeated until t e whole of the dies have been moved over the blank.

In the machine described the comparatively light dies alone require to be moved Y whereas the blank remains stationary. This arrangement is found preferable in carrying out the meent invention; I

It wi of course be understood thatthe die-.holders `may be dispensed with and any the diea ere the total reduction which the blank is required to undergois very considerable it .other suitable mechanism' provided'for actuntin may be found desirable to subdivide theprocess into stages, the blank bein'greduced on' one machine according process to a certain thickness and en reduced still further on a seconddraw-bench with or without intermediate annealing.

1. The improvement in the manufacture of cold-drawn seamless thin-walled metal tubes, which consists in continuousl draw l inEeout a cold hollow blank to a fini ed thin tu '1n substantially uniform stages immediatel succeeding each other.

of cold-drawn seamless thin-walled metal.

tubes, which consitsin drawing out'a cold-'- hollow blank to'a thin tube in an-uninterrupted series of substantially uniform drawing operations. y

3. he improvement in the manufacture of cold-drawn seamless thin-walledmetal tubes, which consists in subjecting a cold .hollow blank on the drawbench toas many i manyjles of slightly and substantially tformi 'dec diameters 'll li cada amd j 'u operation."-

t o the4 resent' e improvement in the manufacture I lllf 5. The improvement in the manufacture Aof cold-drawn seamless thin-walled metal tubes, which consists in ldrawing out n cold hollow blank in close succession between n mandrel and' us many dies of' slightl @und substantially uniformly decreasin d 'me ters-us will suffice to reduce the b zink? to a finished thin tube.

G. The improvement in the manufacture of cold-drawn seamless thin-walled metal tubes, which consists in passim in close successionover a cold hollow bla mounted on u. mandrel1 ns many dies of slightly anfl substantially uniformly decreasing diameters as will sulrice to reduce thin tube.

the blank to a finished 7. The. improvement in the manufacture of'cold-diawn seamless thin-walled metal tubes,l which conslsts 1n mounting n hollow blankA on afmanflrel lund passing over it in close Succession :is innny dies of slightly :HERMANN VON FORSTER.

Witnesses JEAN GRUND, yCARL GRUND. 

